Partners Across The Pacific
For more than three decades, Japan and the United States have been cooperating on bridge engineering research to improve resistance to wind and earthquake damage.
Extreme earthquake and wind phenomena are highly destructive and can devastate transportation networks by destroying structures and severing highway linkages. When seismic or wind events take bridges out of service, highway system connectivity is lost, and efforts to evacuate people or provide rescue services are severely affected.
In the United States, areas of significant seismic activity occur in States and territories located within the Pacific Rim region, but also occur in the New Madrid seismic zone. In addition to earthquakes, the United States experiences destruction caused by catastrophic wind events, including hurricanes and tornados. These events have damaged communities and environments across the Nation.
Because the location, timing, and intensity of seismic activities cannot easily be predicted, investigating the effectiveness of technologies and practices designed to mitigate damages from these often tragic events is difficult and time-consuming.
Japan, as an island nation located in a seismically active zone of the Pacific Rim, has become a leader in research related to earthquakes and wind. The United States, by collaborating with a country that faces similar risks and has sophisticated research capabilities, increases its knowledge base and leverages the resources it assigns to investigate seismic and wind events. In particular, a joint U.S.–Japanese workshop that began 30 years ago provides a framework for collaboration, research, knowledge exchange, and reconnaissance.
“Working together expands the ability of both countries to explore the effects of these natural hazards on highway structures and to increase the resistance of the built environment to the destructive effects of wind and seismic events,” says Acting Administrator Greg Nadeau, head of the Federal Highway Administration.
Roots of the Partnership
Japan and the United States have a long history of information exchanges related to science and technology. Over time, these joint efforts have evolved whenever participating agencies identified specific topics requiring more tightly focused study. To address these research needs and mutual concerns, the two countries established expert panels and task forces.
In 1964, the United States and Japan created the U.S.–Japan Cooperative Program in Natural Resources. This program focused on the need to improve engineering and scientific practices through the exchange of technical data and information, personnel, and research equipment.
The program’s Web site states, “The impetus for forming [it] came from the bilateral Committee on Trade and Economic Affairs, which agreed that exchanging natural resources information, specialists, technical data, and research equipment would greatly benefit the economy and welfare of both countries. . . . The [program] is one of four research exchanges between the United States and Japan. The other three exchanges cover basic science, health/medical affairs, and social/cultural affairs.”
In 1969, the two countries went on to establish the Wind and Seismic Effects Panel to develop a stronger technical focus in this area and to encourage collaboration on the development and exchange of wind and seismic technologies. According to the panel’s Web site, “Panel activities have improved building and bridge standards and codes, and aided structure design and construction in Japan and the United States. In addition, panel members have created and exchanged digitized earthquake records; shared earthquake engineering information and strong motion measurement techniques with seismically active countries; produced database systems for improved prediction of soil liquefaction; and verified mathematical models of storm surge and tsunami warning systems.”
Then, some 15 years later, FHWA joined with Japan’s Ministry of Land, Infrastructure, Transport, and Tourism to address the effects of wind and seismic activity specifically on transportation systems. In 1981, at Tsukuba Science City in Japan, the Wind and Seismic Effects Panel members formed the Task Committee on Wind and Earthquake Engineering for Transportation Systems. Initially the committee focused on research related to the effects of wind resistance and seismic events on traffic facilities. FHWA was designated the lead U.S. agency on the committee, and bridge engineer delegates included a cross section of stakeholders: Federal, State, and local government agencies; academia; industry; and professional organizations.
The annual U.S.–Japan Bridge Engineering Workshop grew out of that committee, which held the first workshop in 1984, in Tsukuba Science City. Since then, the committee has held 30 annual bridge engineering workshops, alternating in location between Japan and the United States. U.S. locations have included Chicago, IL; St. Louis, MO; San Diego, CA; Seattle, WA; and Washington, DC. In Japan, the meetings are always held at Tsukuba Science City. During this 30-year collaboration, the University of Nevada in Reno, under contract with FHWA, has coordinated and organized U.S. participation in the workshops.
Joint Bridge Engineering Workshops
Activities at the annual workshops are usually spread over 2.5 days. This timeframe allows for extensive face-to-face meetings, presentations of formal technical papers, and site visits. Also incorporated into the workshop structure is a half-day bilateral, government-to-government meeting. This meeting provides government experts with an opportunity to discuss technical and policy issues in an informal environment.
Topics of Workshop Presentations
|Topic||Number of Papers||Percent of Total Number of Papers|
|Maintenance, inspection, and strengthening||188||18|
|Design and analysis||165||16|
|Source: FHWA. Percentages are approximate due to rounding.|
Approximately 900 individual participants from both countries have attended the workshops over the past 30 years, averaging about 55 participants per meeting. Counting those who have attended multiple meetings makes participation numbers higher. Since 1984, more than 1,000 papers have been presented and later published in the workshop proceedings. On average, Japanese and U.S. participants present 36 papers at each workshop. The locations of site visits include bridges, airports, research laboratories, and university research facilities.
Sharing information on various practices and technologies provides an opportunity to explore diverse approaches to meeting similar challenges and technical issues encountered in bridge engineering. Through the annual workshops, U.S. and Japanese bridge engineers have identified potential technological advances, many of which were implemented into practice. For example, both Japan and the United States developed seismic retrofitting and seismic isolation technologies at approximately the same time.
Other Seismicity Topics
U.S. exchanges at the workshops have included presentations on performance-based seismic design and retrofit, which strive to ensure that structures meet prescribed performance criteria under seismic loads. Other topics have included the use of buckling braces such as stiffeners to resolve stability issues and highlights from Washington State’s seismic retrofit program.
Papers presented by Japanese engineers have addressed issues such as carbon fiber-reinforced polymer sheet jacketing on the Tsurumi Tsubasa cable-stayed bridge; the use of carbon fiber-reinforced polymer and steel plate sheet jacketing; and the use of anti-seismic devices and isolation bearings in the Honshu-Shikoku bridges.
The United States has successfully implemented retrofitting measures in high-seismicity areas in California, Oregon, and Washington. These retrofitting measures include restrainers, steel and concrete jackets, as well as fiber-reinforced polymer jackets for sheer strengthening and ductility enhancement of columns. Additional state-of-the-art and state-of-the-practice technologies exchanged between the two countries include those related to wind design for long-span bridges; advanced materials; bridge management; and bridge inspection, assessment, and maintenance.
Cooperative Research Program
The annual workshops also have provided a forum through which U.S. and Japanese engineers participate on cooperative research projects. In addition to addressing issues of mutual concern, joint research projects facilitate collaboration among researchers in both countries, increase the exchange of research findings, and encourage sharing of state-of-the-art practices.
These cooperative research programs have resulted in the following achievements:
- The development of draft experimental testing guidelines for verification of seismic performance of bridges, including quasi-static cyclic loading tests and shake table tests for bridge columns.
- A comparative evaluation of U.S. and Japanese seismic control systems, testing protocols, and design of highway bridges.
- Collaborative improvements to the numerical modeling of tsunami effects, and validation of these methodologies through wave basin experiments.
- U.S.–Japanese joint reconnaissance of bridges damaged by earthquakes.
In addition to the cooperative research programs, the two countries held a number of specialty workshops in the 1990s that focused on specific areas such as earthquake protective systems and seismic retrofitting techniques. The engineers convened seven such events between 1990 and 1996. Exchanges on technologies and practices greatly accelerated the adoption of protective systems in both countries and the improvement and implementation of retrofit strategies. One study, for example, resulted in engineers in both countries better understanding the advantages of different approaches to seismic retrofitting and applying them to bridge design and construction.
Each year, millions of earthquakes occur across the globe. Most are insignificant, discernable only through use of sophisticated scientific equipment. The severe, destructive seismic event is uncommon, and its location and magnitude are difficult to predict.
Recent Earthquakes Visited by Reconnaissance Teams
|January 17, 1994||Northridge, CA, USA||6.7||
|January 17, 1995||Awaji Island, Japan||6.9||
Maule (Chile) Earthquake
|February 27, 2010||Maule region, Chile||8.8||
Great East Japan (Tohoku) Earthquake
|March 11, 2011||Tohoku region, Japan||9.0||
|Note: The financial impacts are from the time of the event and not adjusted for inflation. Source: FHWA.|
This lack of frequency and predictability makes learning from earthquakes difficult because data are accrued slowly over time. As a result, sharing knowledge and technologies on bridge performance and behavior becomes even more important. When a significant earthquake does occur, typically it becomes a focus for researchers and engineers. They come together to share and exchange observations on bridge damage, structural performance, and evaluation of design and analysis practices.
The relationships built through the bridge engineering workshops are essential to facilitating extensive joint U.S. and Japanese reconnaissance efforts following severe earthquakes. Joint reconnaissance occurred after the Northridge Earthquake (California, 1994); Hyogoken-Nanbu Earthquake (Kobe, 1995); Maule Earthquake (Chile, 2010); and the Great East Japan Earthquake (Tohoku, 2011). The reconnaissance teams investigated damage that included collapsed bridge spans and sections, steel girder buckling, shear failure of abutment walls, and flange damage in concrete girders.
The Great East Japan Earthquake, the most powerful ever recorded in Japan, triggered massive tsunami waves, which pushed seawater as far as 6 miles (9.7 kilometers) inland. The quake registered a magnitude of 9.0 on the Richter scale and is one of the largest ever recorded. Strong ground motion, tsunami inundation, and soil liquefaction damaged approximately 200 highway bridges and numerous railroad bridges.
A U.S. reconnaissance team conducted a post-earthquake investigation on bridge performance and evaluated the structural damage, which included unseated spans, foundation scour, ruptured bearings, column shear failures, and approach fill settlements. As a result of the reconnaissance, new research programs are underway to study the duration effects of strong ground motion and tsunami loads. The departments of transportation in the western coastal States of Alaska, California, Hawaii, Oregon, and Washington and FHWA are conducting a joint study that will involve cooperating with Japan’s Public Works Research Institute to share the research results. The objective of the study is to develop bridge design guidelines for the estimation of tsunami loads on highway bridges. The work is proposed to include verification of the guidelines by model testing or comparison with observed results to calibrate the predictive capability of numerical models for analysis of tsunami loads on coastal bridges. Generalized bathymetry (the study of underwater depths) and topography parameters will be modeled analytically and replicated experimentally.
Sharing experiences on prompt response and recovery from devastating earthquakes and tsunamis is valuable in preparing for, responding to, and recovering from such natural disasters. Bridge engineers and public officials have benefited from the lessons learned from events worldwide. The knowledge gained through decades of information exchange and continuous revision of seismic design specifications in both countries presumably have helped lessen the loss of life and property during extreme events.
Oregon’s Perspective On the Workshops
The Oregon Department of Transportation (ODOT), an active participant in the annual workshops, has benefited significantly from the information and technology exchanges, according to Bruce Johnson, State bridge engineer at ODOT.
“The workshops provide an opportunity to learn and share information and experiences with our Japanese counterparts,” he says. “The specialists and experts from the Japan side are very open and willing to share lessons learned from their experience with recent extreme earthquakes and tsunamis.”
Johnson continues, “The two most important things I’ve learned were how structural detailing can affect a bridge’s survivability from tsunami waves, and how proper preparation can improve response and recovery from such a devastating event. I was particularly interested to see and hear about the force of the tsunami waves and the extent of damage to transportation structures along the coast.” Johnson notes that ODOT has been conducting research at Oregon State University to predict tsunami wave characteristics and resulting forces on highway structures.
“However, we are far from being able to quantify the damage we have witnessed in Japan,” he says. “A very important thing I learned was that the structural resistance to tsunami wave forces is a bit like structural resistance to seismic forces. Some structures are much more resistant--not due to strength, but due to the structural detailing involving continuity, the height of the structure, and the area of the horizontal projection. This information will be very useful as Oregon continues to develop tsunami design guidelines for coastal bridges.”
Over the years, researchers and engineers from Japan and the United States have established professional networks focused on specific technical subjects. These relationships are effective in helping experts remain current on technologies and practices, and aware of emerging innovations in bridge engineering.
Many participants consider the workshops and networking groups as opportunities to conduct brainstorming sessions to discuss questions that are normally difficult to cover in written communication or published reports. The friendships formed between U.S. and Japanese participants also provide a strong foundation for new generations of bridge engineers who are mentored by the more experienced professionals.
Professor David Sanders of the Department of Civil and Environmental Engineering at the University of Nevada in Reno expresses appreciation for the opportunity to network on professional and personal levels with the Japanese members of the Public Works Research Institute and the National Institute for Land and Infrastructure Management.
“As we have gotten to know each other better, the ability to share valuable information has become much easier,” he says. “This increased ability to share is now not only true for Japanese members that we have known for a long time, but also new contacts that we meet each time.”
He adds that the exchange of information occurs during study tours as well as the workshops. “The Great East Japan Earthquake subjected a significant area to large ground motions and then to the tremendous effect of the tsunami. Many structures, including those retrofitted after the 1995 Kobe earthquake, did well. Older structures that had not been retrofitted suffered damage typically near supports.”
Reconnaissance teams gather potentially perishable data and metadata, such as original design plans, construction drawings, and prior performance histories, to better understand how infrastructure performed during seismic events. Some structures perform well while others fail miserably. The reconnaissance teams try to document this performance, compared with the basis under which the structures were originally designed and constructed, and then report on the findings. The teams also indicate opportunities for improvement, areas for further investigation, and possible mitigation measures.
U.S. reconnaissance teams to Japan have included efforts undertaken by FHWA, but also by the American Society of Civil Engineers, the Earthquake Engineering Research Institute, the National Science Foundation, and others. The Japanese helped facilitate logistics and the collection of data, and helped to confirm assumptions and documentation during the preparation of subsequent reports.
–Prepared with the help of Ian Friedland, Turner-Fairbank Highway Research Center
Sanders continues: “It is important that the United States continue to work to retrofit our structures and look at the force path closely. Because the damaged structures had been retrofitted, they were brought back into service quickly. It is a good lesson for us, to be sure that we are prepared and know how to respond quickly.”
Sanders also notes the impact of liquefaction. “Again, the Japanese have responded quickly to repair the damage. In one area, only a person who knew what happened would have been able to tell that there was damage due to settlement.”
One of the key issues, he adds, is the level of event that structures should be designed for, especially in different regions of the United States. Japan has the same issue. “We can come up with better solutions working together,” Sanders says.
Professional Exchange Program
In addition to networking, another benefit stemming from the workshops is a professional exchange program. Under this initiative, engineers and researchers from one country are invited to participate in technical visits to the other, and these professional exchanges range from 1 week to 1 year in duration. The exchanges provide opportunities to take part in joint research studies or pursue other technical interests.
Since 1983, a total of 23 engineers and researchers from both countries have participated in the professional exchange program. During these assignments, participants become familiar with current practices in the country they are visiting.
Continuing the Legacy
The extensive cooperation between the United States and Japan has produced synergistic approaches, including analysis methods such as seismic isolation design. Both countries have common interests in developing approaches that will reduce loss of life and preserve the transportation infrastructure in the face of devastating seismic and wind events.
The annual U.S.–Japan Bridge Engineering Workshop has provided a venue for increasing what is known about the effects of seismic and wind events on the built environment. The workshop also has created an opportunity to learn about practices or technologies that help mitigate damage, and to share experiences leading to prompt response and recovery.
The relationships forged over three decades of collaboration have proven to be mutually beneficial to both countries. Specific benefits include the following:
Cost sharing. Both countries face similar challenges in advancing bridge safety and performance, and have completed several cooperative research tasks on these topics. Examples include comparison of seismic design codes and experimental tests of bridge columns. Test results were used to improve bridge seismic safety, reducing costs by nearly 50 percent.
Technology and information sharing. The 2011 Tohoku Earthquake in Japan provided critical information on how bridges performed under the tsunami wave’s impact. Leveraging the relationships developed at the U.S.–Japan workshops, FHWA, in collaboration with State DOTs, is conducting a pooled-fund study on Validation of Tsunami Design Guidelines for Coastal Bridges. Japanese researchers are supporting this research effort.
Joint reconnaissance and access to damaged sites. Information gathered from joint reconnaissance teams organized as part of the U.S.–Japan workshops was used to update the bridge design codes to improve seismic safety. For example, soon after the 1995 Kobe Earthquake, a joint bridge reconnaissance was organized to investigate bridge performance. The results collected on bridge performance with isolation bearing and steel bridge piers (buckling) were very beneficial in the validation of the bridge design codes.
Both countries are working to further strengthen cooperation. For future workshops, the countries will evaluate the implementation of various communications media, including the Internet and cloud storage, to improve the efficiency and effectiveness of workshop sessions and activities.
Nelda Bravo recently retired from FHWA after a productive career that included tenures in the Office of International Programs, Turner-Fairbank Highway Research Center, and the Bureau of Transportation Statistics.
Phil Yen is a principal bridge engineer with FHWA’s Office of Bridges and Structures where he focuses on structural dynamics. He also serves as the U.S. chair of the workshop series. He received his master’s and doctorate in civil engineering from the University of Virginia and is a registered professional engineer in Virginia.
Agnes Vélez is a transportation specialist with FHWA’s Office of International Programs where she oversees activities with Israel, Japan, and the World Road Association. She earned a B.A. in communications and an M.B.A. in marketing from Loyola University in New Orleans.
For more information, see www.fhwa.dot.gov/bridge or contact Agnes Vélez at 202–366–5771 or firstname.lastname@example.org or Phil Yen at 202–366–5604 or email@example.com.